Diagnosis of Pulmonary Artery Embolism: Comparison of Single-Source CT and 3 rd Generation Dual-Source CT using a Dual-Energy Protocol Regarding Image Quality and Radiation Dose

Abstract

Purpose To compare radiation dose, subjective and objective image quality of 3rd generation dual-source CT (DSCT) and dual-energy CT (DECT) with conventional 64-slice single-source CT (SSCT) for pulmonary CTA. Materials and Methods 180 pulmonary CTA studies were performed in three patient cohorts of 60 patients each. Group 1: conventional SSCT 120kV (ref.); group 2: single-energy DSCT 100kV (ref.); group 3: DECT 90/Sn150kV. CTDIvol, DLP, effective radiation dose were reported, and CT attenuation (HU) was measured on three central and peripheral levels. The signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. Two readers assessed subjective image quality according to a five-point scale. Results Mean CTDIvol and DLP were significantly lower in the dual-energy group compared to the SSCT group (p<0.001 [CTDIvol]; p<0.001 [DLP]) and the DSCT group (p=0.003 [CTDIvol]; p=0.003 [DLP]), respectively. The effective dose in the DECT group was 2.79±0.95mSv and significantly smaller than in the SSCT group (4.60±1.68mSv, p<0.001) and the DSCT group (4.24±2.69mSv, p=0.003). The SNR and CNR were significantly higher in the DSCT group (p<0.001). Subjective image quality did not differ significantly among the three protocols and was rated good to excellent in 75% (135/180) of cases with an inter-observer agreement of 80%. Conclusion Dual-energy pulmonary CTA protocols of 3rd generation dual-source scanners allow for significant reduction of radiation dose while providing excellent image quality and potential additional information by means of perfusion maps.